Small-incision lenticule extraction (SMILE) is a refractive
procedure approved by the United States Food and Drug Administration (FDA) for
the correction of myopia and myopic astigmatism. The procedure is performed
using the VisuMax Laser System and uses a femtosecond laser to incise and carve
a lenticule within the corneal stroma without creating a corneal flap. The
lenticule is then excised from the cornea to achieve refractive correction.
As with other refractive surgeries, a subset of SMILE
patients requires follow-up enhancement. Enhancement may be required due to a
delayed myopic regression or an initial under- or overcorrection. In these
cases, the most common enhancement procedures are photorefractive keratectomy
(PRK) and LASIK.
This retrospective, single-site study by Moshirfar et al
reviewed all cases of primary SMILE at Hoopes Vision in Draper, Utah between
March 14, 2017 and April 8, 2022 to identify any cases that required follow-up
enhancement. Primary SMILE was performed using Visumax 500 kHz femtosecond
laser (Carl Zeiss Meditec, Jena, Germany). All enhancements were performed with
alcohol assisted PRK, using a WaveLight EX500 excimer laser (Alcon
Laboratories, Inc., Fort Worth, TX).
Four hundred and five eyes underwent primary SMILE, of which
15 later underwent PRK enhancement (enhancement rate of 3.7%). No significant
difference in pre-SMILE data was identified between the enhancement and
non-enhancement groups.
Following primary SMILE, 13 eyes (87%) had an uncorrected
distance visual acuity (UDVA) of 20/40 or better, and none had a UDVA of 20/20
or better.
After one year of post-enhancement follow-up, all eyes had a
UDVA of 20/40 or better, and 13 eyes (87%) had a UDVA of 20/20 or better.
All were within one diopter of target spherical equivalent
(SEQ), 13 (87%) were within 0.50 D, and 10 (67%) were within 0.25 D.
Of those with 12-month follow-up data, none had UDVA worse
than corrected distance visual acuity (CDVA), and none had lost lines of CDVA.
Efficacy and safety indices were 1.03 and 0.99, respectively.
This study retrospectively reviewed 15 cases of PRK
enhancement following SMILE. The rate of enhancement was 3.7%. Though limited
by the small sample size and retrospective nature of the study, this result
fits within the range reported in the literature, which suggests that
ophthalmologists may anticipate an enhancement rate of one to seven percent
following SMILE. In these cases, PRK is a safe and effective procedure for
enhancement of SMILE.
Source: Moshirfar et al; Clinical Ophthalmology 2022:16